Question 644696
{{{t^2-2t-15}}}...use quadratic formula


{{{t = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}


{{{t = (-(-2) +- sqrt( (-2)^2-4*1*(-15) ))/(2*1) }}}


{{{t = (2 +- sqrt( 4+60 ))/2 }}}


{{{t = (2 +- sqrt( 64 ))/2 }}}


{{{t = (2 +- 8)/2 }}}


solutions:


{{{t = (2 + 8)/2 }}}

{{{t = 10/2 }}}

{{{t = 5 }}}

or

{{{t = (2 - 8)/2 }}}

{{{t = -6/2 }}}

{{{t = -3 }}}

{{{ graph( 600, 600, -10, 10, -20, 10, x^2-2x-15) }}}